The present invention relates to a coatings composition comprising a stable aqueous dispersion of vinyl acetate functionalized polymer particles adsorbed to pigment particles in an above-critical pigment volume concentration (PVC) paint formulation.
Coating formulations are complex mixtures of polymers particles (binder), pigments, extenders, and additives. The pigment of choice in most coatings formulations is TiO2, which is effective for creating opacity, but expensive. The expense can be mitigated somewhat by functionalizing the binder with phosphate groups to promote adsorption of the binder particles to TiO2 particles to form composites with increased spacing between the pigment particles, thereby providing a mechanism for reducing the levels of expensive TiO2 to achieve the same degree of hiding.
Especially attractive binders for architectural coatings are vinyl acetate polymers and copolymers, which are known to have high scrub resistance at relatively low cost. Vinyl acetate polymers functionalized with phosphate groups are especially desirable as film-forming polymers due to the cost benefits provided by reduced TiO2 usage. Cost benefits of vinyl acetate based paints are further realized in above critical paint formulations, which are widely used in spite of their relatively poor performance. It would desirable to improve performance, particularly hiding (opacity), in these above-critical vinyl acetate based paint formulations economically.